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NCSU CH 202 - Lab 07 In Lab

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1. 35/35 points Last Response | Show Details All Responses Notes Data Tables and In-Lab QuestionsData Table A. pH Data for Acetate Buffers (Direct Method)Solution # mL of 0.60 M HC2H3O2mL of 0.60 M NaC2H3O2pH1A 30 02.66 [2.66]2A 30 104.14 [4.14]3A 0 306.62 [6.62]4A 10 305.13 [5.13]5A 20 204.66 [4.66]Question 3. Based on your observations in Part A, select all of the following statements that are true. [_] [_] the pH increases as the mL of base added increases [_] [_] the pH decreases as the mmol of acid added increases [x] [x] the pH increases as the mmol of base added minus the mmol of acid added increases [_] [_] the pH increases as the mmol of base added increases [x] [x] the pH increases as the mL of base added minus the mL of acid added increases [x] [x] the pH decreases as the mL of acid added minus the mL of base added increases [x] [x] the pH decreases as the mmol of acid added minus the mmol of base added increases [_] [_] the pH decreases as the mL of acid added increasesPart B. Step 1 directs you to add 30 mL of 0.60 M aceitc acid to a clean 100 mL beaker. How many mmol of acetic acid are present in your sample?mmol HC2H3O2 = 18 [18]Data Table B. pH Data for Acetate Buffers (Indirect Method)Solution#mL ofNaOHaddedtotal mLNaOHaddedpHtotal mmolNaOH addedBuffer?1B 0 02.68[2.68]0.0 [0.0](_) (_)yes(o) (o)no 2B 4 43.73[3.73]4.0 [4.0](o) (o)yes (_) (_)no 3B 5 94.08[4.08]9.0 [9.0](o) (o)yes (_) (_)no 4B 6 154.31[4.31]15 [15](o) (o)yes (_) (_)no 5B 10 254.31[4.31]25 [25](_) (_)yes (o) (o)no Part B. For Part B, you are asked to assess which of the mixtures are buffers. Which of the following are true about the solutions you labeled as buffers?[_] [_] they contain only acetate ions [_] [_] they contain equal amounts of acetate ions and acetic acid [_] [_] they contain more acetic acid than acetate ions [x] [x] they contain both acetate ions and acetic acid [_] [_] they contain more acetate ions than acetic acid [_] [_] they contain only acetic acidData Table C. Data for Phosphate BufferpH Assigned7.50 [7.50]actual mass of Na2HPO4·7H2O used3.006 [3.006] gother phosphate compound used(o) (o)NaH2PO4·H2O (_) (_)Na3PO4·12H2O calculated mass of other phosphate compoundto use0.767 [0.794] gactual mass of other phosphate compoundused0.767 [0.767] ginitial measured pH of buffer6.70 [6.70]action taken(_) (_) added acid (o) (o) added base final measured pH of buffer7.51 [7.51]2. 15/15 points Last Response | Show Details All Responses Notes Type your name in the answer box. Your instructor will enter your discretionary lab grade in the score box for this question. Mike McSherry, Amit PatelKey: Enter a discretionary score for this student, if lower than full


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NCSU CH 202 - Lab 07 In Lab

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